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General Forums => The Mess Hall => Topic started by: zworld on December 31, 2006, 10:37:06 AM
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There was no manual with my Jeep, can anyone tell me what viscosity to run? 5w30, 10w40? I guess I need to find a manual.
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Oil viscosity refers to how easily oil pours at a specified temperature. Thinner oils have a water-like consistency and pour more easily at low temperatures than heavier, thicker oils that have a more honey-like consistency. Thin is good for easier cold weather starting and reducing friction, while thick is better for maintaining film strength and oil pressure at high temperatures and loads.
The viscosity rating of a motor oil is determined in a laboratory by a Society of Automotive Engineers (SAE) test procedure. The viscosity of the oil is measured and given a number, which some people also refer to as the "weight" (thickness) of the oil. The lower the viscosity rating or weight, the thinner the oil. The higher the viscosity rating, the thicker the oil.
MOTOR OIL VISCOSITY RATINGS
Viscosity ratings for commonly used motor oils typically range from 0 up to 50. A "W" after the number stands for "Winter" grade oil, and represents the oil's viscosity at zero degrees F.
Low viscosity motor oils that pour easily at low temperatures typically have a "5W" or "10W" rating. There are also 15W and 20W grade motor oils.
Higher viscosity motor oils that are thicker and better suited for high temperature operation typically have an SAE 30, 40 or even 50 grade rating.
These numbers, by the way, are for "single" or "straight" weight oils. Such oils are no longer used in late model automotive engines but may be required for use in some vintage and antique engines. Straight SAE 30 oil is often specified for small air-cooled engines in lawnmowers, garden tractors, portable generators and gas-powered chain saws.
MULTI-VISCOSITY MOTOR OILS
Most modern motor oils are formulated from various grades of oil so the oil will have the best characteristics of both thick and thin viscosity oils. Multi-viscosity oils flow well at low temperature for easier starting yet retain enough thickness and film strength at high temperature to provide adequate film strength and lubrication.
A thin oil such as a straight 10W or even a 20W oil designed for cold weather use would probably not provide adequate lubrication for hot weather, high speed driving. Likewise, a thicker high temperature oil such as SAE 30 or 40 would probably become so stiff at sub-zero temperatures the engine might not crank fast enough to start.
Multi-viscosity grade oils have a wide viscosity range which is indicated by a two-number rating. Popular multi-viscosity grades today include 5W-20, 5W-30, 10W-30, 10W-40 and 20W-50. The first number with the "W" refers to the oil's cold temperature viscosity, while the second number refers to its high temperature viscosity.
Note: Motor oils that have a wider range viscosity rating such a 5W-30 are blended with more base stocks and additives. Because of this, it may be harder for a wider range oil to remain in grade as the miles accumulate (which is why GM does NOT recommend using 10W-40 motor oil -- they say it breaks down too quickly and does not say in grade as long as 10W-30 or 5W-30). Also, an oil with a lower winter rating like 5W-30 or 0W-30 will contain a higher percentage of thinner base stock oil. This requires more viscosity improver additive to achieve a the same high temperature rating of a 10W-30 or straight 30 oil.
(http://i24.photobucket.com/albums/c33/SMC4WD/oil_chart.jpg)
Most vehicle manufacturers today specify 5W-30 or 10W-30 motor oil for year-round driving. Some also specify 5W-20. Always refer to the vehicle owners manual for specific oil viscosity recommendations, or markings on the oil filler cap or dipstick.
As a rule, overhead cam (OHC) engines typically require thinner oils such as 5W-30 or 5W-20 to speed lubrication of the overhead cam(s) and valve-train when the engine is first started. Pushrod engines, by comparison, can use either 5W-30, 10W-30 or 10W-40.
As mileage adds up and internal engine wear increases bearing clearances, it may be wise to switch to a slightly higher viscosity rating to prolong engine life, reduce noise and oil consumption. For example, if an engine originally factory-filled with 5W-30 now has 90,000 miles on it, switching to a 10W-30 oil may provide better lubrication and protection. The thicker oil will maintain the strength of the oil film in the bearings better so the engine will have more oil pressure. This will also reduce engine noise and reduced bearing fatigue (which can lead to bearing failure in high mileage engines).
For sustained high temperature, high load operation, an even heavier oil may be used in some situations. Some racing engines use 20W-50, but this would only be recommended for an engine with increased bearing clearances. Increasing the viscosity of the oil also increases drag and friction, which can sap horsepower from the crankshaft. That's why 20W-50 racing oil would not be the best choice for everyday driving or cold weather operation for most vehicles. The latest trend in racing is to run tighter bearing clearances and use thinner oils such as 5W-30 or 5W-20 to reduce friction and drag.
By Larry Carley c2006
http://www.aa1car.com/library/oil_viscosity.htm
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Ok, my question was what does the factory recommend for the 2.5, again I do not have a manual. thanks
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5w 30 for the winter, 10w30 for the summer.
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Thanks Talboy
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Can't go wrong with 5w30 or 10w30; use synthetic if possible - Mobil 1, Castrol, Redline, Amsoil.
I'm personally trying out the Mobil 1 "0W20" Synthetic for the winter - it's thinnner than virgin olive oil :lol: But, may go back to 10W30.
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I run 10W30 in winter and 10W40 in summer.
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I run Delvc 15w-40 or Rottela T 15w-40 with a Wix or Pureulator Pure One filter...
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wow!
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i use 5-40 rotella synthetic. it come by the gal. so it just the right size for the 4 banger. it runs $14 at wally world. it is a good deal & happens to be one of the best oils made. i usually change it every 5000 miles or so. the older designs of these pushrod engines don't need that super thin stuff, unless you are in an extremly cold climate (i am in florida). when using those 20 weights, you will notice a lot of noise coming from the vlavetrain. the 5-20 weight oils are only used to slightly increase the fleet fuel mileage (like .1 or .2 nothing noticeable) for CAFE regulations. an example would be the ford f-150. it specifies 5-20 now, but several years ago it specified 5-30 with the same exact engine. after the change, engine longevity decreased. i think as far as dino oil goes, 10-30 castrol is about the best.
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I'm running 10W30 Mobil 1 Extended Performence and I am begining to hear some rattling at ~3000 miles. ??? My engine has almost 180K miles. Should I be using 10W40? Is Royal Purple worth $7/quart?
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I'm running 10W30 Mobil 1 Extended Performence and I am begining to hear some rattling at ~3000 miles. ??? My engine has almost 180K miles. Should I be using 10W40? Is Royal Purple worth $7/quart?
I'd probably try running the thicker oil, 10w40 might quiet it down. I don't really recommend the exotic oils since getting them can be a pain and the additional cost isn't usually worth it on a Jeep, especially one with high mileage. Also, you have to worry about leakage when switching from dino oil to synthetics. There are less detergents in the dino oils so you get deposits around seals and other areas. Running an oil with more detergents can clean this away and exposed dry, cracked seals.
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I ussually go with 10W-40 or 20W-40. But then again, I live in Miami, so the seasons here are the HOT season and the HOTTER season! I use synthetics, but keep the weight up to avoid leaking. Keep in mind that a lot of damage is done at start-up on cold mornings, when the oil is thicker because of temperature, and all the oil has drained from the engine, so depending on your temperature, you may want to go with thicker or thiner oil. the W especification means Winter, so it means that the oil behaves like a thiner oil at very low temps (for example, a 10W-30 oil will behave like a SAE 10 in winter temps, and a SAE 30 at operating temps, so the oil gets to the engine as quickly as a thiner SAE 10 would, but once the engine gets to operating temperature, the oil is as thick as a SAE 30 and protects as one).
Felipe
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I run 10W-30 year around, valvovine max life. I know my spelling is bad.
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:clap: Thanks guys. I'll go 10W40 next time the oil is changed.
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heh this thread reminds me that my next oil change is coming up 8)
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in summer, our low is like 60~80 (we have had a low of 90 though!!!!!!) and our high as much as 120 (although mostly 115), should I run 20W-50 or 15W-40? Today was our first break of 100 for the year (and came two weeks later than last year, global warming... haha... haha...), it was 101 and I'm thinking It would be best to get a thicker oil soon.
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heh this thread reminds me that my next oil change is coming up 8)
I've got to do one as well. I have the oil and the filter ready. This time I went with a Puralator so I 'pay a little now instead of more later.' :lol:
I have a Fram Sure Drain on me Jeep so the only dirty part is removing the oil filter. I just let it drain into a 1ltr bottle, clamp it off then fill up the second one. No more oily oil pans to clean. :fitz:
Now I just have to get off my butt and change the oil.
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in summer, our low is like 60~80 (we have had a low of 90 though!!!!!!) and our high as much as 120 (although mostly 115), should I run 20W-50 or 15W-40? Today was our first break of 100 for the year (and came two weeks later than last year, global warming... haha... haha...), it was 101 and I'm thinking It would be best to get a thicker oil soon.
I would go with the 15W-40, but both should work just fine... If you plan to work your engine hard (ie. hitting lots of trails, towing, etc.) you mey want to go for the higher viscosity, but otherwise the 15W-40 should be enough.